A kind of independent micro light striking module for CIS wafer test probe card

Abstract

The application relates to a self-contained micro light-emitting module for a CIS wafer test probe card, which comprises a main light source, a locking ring, a light guide column, a light uniformizing sheet and an imaging lens arranged in sequence along a light path; the locking ring is in a sleeve structure, is sleeved on the outer side of the upper end of the light guide column and can axially slide, the total light amount of a single channel can be adjusted by changing the distance between the main light source and the upper end surface of the light guide column; the inner wall of the light guide column is in a hexagonal polyhedral structure, light rays complete three-dimensional light beam mixing through multiple total internal reflections inside the light guide column; the light uniformizing sheet adopts a high-haze body scattering material to perform secondary angle scattering on the mixed light beams; the imaging lens modulates the light beams after light uniformization into main light ray angles, imaging spot diameters and relative illuminances matched with the CIS wafer to be measured, and projects the modulated light beams to the photosensitive surface of the CIS wafer to be measured; a bearing shell is fixed on the outer side to form micro closed light path channels which are independent of each other and do not interfere with each other. The application can individually calibrate the illuminance of each channel and adapt to various CIS wafer test working conditions.

Description

Technical Field

[0001] This invention relates to the fields of semiconductor testing and computer vision optics, and more particularly to an independent miniature illumination module for CIS (image sensor) wafer test probe cards. Background Technology

[0002] In CIS wafer multi-site parallel testing processes, each CMOS chip under test within a high-density chip array requires the probe card to provide high illumination, high spot uniformity, and high-precision principal ray angle (CRA) matching. Existing probe card illumination solutions have the following significant drawbacks:

[0003] 1. Single-stage homogenization suffers from significant light loss and severe edge vignetting: Traditional lighting schemes rely solely on a single-layer diffuser for passive scattering. Due to the high aspect ratio of the physical openings in the probe card's internal mechanical housing (Holder), light rays from the edge field of view are easily intercepted by the inner walls of the Holder, causing severe mechanical vignetting and field-of-view avulsion (FOVClipping), resulting in a drastic decrease in illuminance at the edge of the CIS chip's image plane. Using only a single-layer homogenizer in conjunction with the lens results in a severe mismatch between the eccentricity of the light field and the physical aperture of the high aspect ratio channel. High-angle beams are significantly clipped and absorbed within the transmission channel, leading to a substantial reduction in overall luminous flux and illuminance transmission efficiency.

[0004] 2. Global collimation systems are bulky and lack independent channel fine-tuning capabilities: If a large-aperture compound eye lens is used for global collimation, it will not only significantly increase the system size and cost, but also make it impossible to adjust the image plane illuminance and match the main beam angle of each independent microchannel in the array individually, making it difficult to adapt to the testing requirements of CIS wafer chips of different specifications.

[0005] 3. PCB processing and module assembly tolerances can lead to inconsistent module heights, which in turn cause differences between different channels in traditional lighting solutions. These differences cannot be adjusted individually, thereby reducing the yield and accuracy of chip testing.

[0006] 4. The illuminance consistency between independent test channels is poor. Traditional calibration methods can only be achieved by repeatedly trying and correcting by disassembling and replacing light-diffusing sheets with different transmittance. The debugging process is cumbersome and the production efficiency is extremely low.

[0007] 5. The optical path distance between the light source and the lens is limited by the structure of the PCB and surrounding components. Traditional optical paths cannot simultaneously meet the requirements of high illumination output and the stacking height of the miniature lens module. Summary of the Invention

[0008] This invention provides an independent micro-illumination module for CIS wafer test probe cards to solve the above-mentioned technical problems.

[0009] To address the aforementioned technical problems, this invention provides an independent miniature illumination module for a CIS wafer test probe card, comprising a main light source, a locking ring, a light guide column, a light homogenizer, an imaging lens, and a supporting housing.

[0010] The main light source is located on the top of the module;

[0011] The locking ring is a sleeve structure, which is fitted onto the outer side of the upper end of the light guide post and can slide along the optical path axis. The total amount of light entering a single channel can be adjusted by changing the distance between the main light source and the upper end face of the light guide post.

[0012] The light guide post is coaxially arranged below the locking ring. The inner wall of the light guide post has a hexagonal polyhedral structure. Light undergoes multiple total internal reflections inside the light guide post to complete three-dimensional beam mixing.

[0013] The light-diffusing sheet is installed between the lower end of the light guide post and the imaging lens. The light-diffusing sheet is made of a high-haze volume scattering material to perform secondary angular scattering of the mixed light beam, thereby satisfying the field of view angle of the imaging lens.

[0014] The imaging lens is coaxially positioned below the homogenizing plate and is used to modulate the beam emitted after homogenization into a principal ray angle, imaging spot diameter, and relative illuminance that match the CIS wafer under test, and project it onto the photosensitive surface of the CIS wafer under test.

[0015] The supporting housing encloses and fixes the main light source, locking ring, light guide column, light homogenizer and imaging lens, forming a miniature closed optical path channel that is independent of each other and does not interfere with each other.

[0016] Preferably, the main light source is a planar Lambertian light source, used to output a uniform and continuously adjustable beam.

[0017] Preferably, the locking ring is provided with a locking component for fixing its axial position after the locking ring has been slidably adjusted into place.

[0018] Preferably, the outer wall of the locking ring is provided with scale markings for quantifying the axial sliding distance.

[0019] Preferably, the inner wall of the light guide column is provided with a high-reflectivity film.

[0020] Preferably, the light guide post includes a variety of fixed axial length specifications, and different specifications of light guide posts can be selected and replaced based on the thickness of the probe card PCB and the aspect ratio of the channel opening.

[0021] Preferably, the imaging lens is a mobile phone lens.

[0022] Preferably, the housing is provided with multiple positioning steps, and the main light source, locking ring, light guide, light homogenizer and imaging lens are respectively limited by the positioning steps.

[0023] Preferably, it also includes an ISP processor, which is used to acquire and process the imaging image data output by the CIS wafer under test, and calculate the illuminance deviation and principal ray angle deviation of each channel based on the imaging image data.

[0024] Preferably, the operator controls the locking ring to slide along the optical path axis based on the deviation value output by the ISP processor.

[0025] Compared with existing technologies, the independent micro-illumination module for CIS wafer test probe cards provided by this invention has the following advantages:

[0026] 1. Achieve lossless uniform light distribution in the spatial domain, adapting to high aspect ratio structures and eliminating mechanical vignetting and field-of-view interference. Traditional solutions in high aspect ratio PCBs and probe card carrier channels are prone to edge light interception by the aperture walls. This invention utilizes a hexagonal polyhedral light guide post, employing a total internal reflection (TIR) ​​mechanism in the spatial domain to perform high-frequency, lossless transmission and mixing of the initial input Lambertian light in three-dimensional space, resulting in a highly uniform top-hat spatial light spot. Furthermore, the axial length of the light guide post can be flexibly customized according to different probe card PCB thicknesses and test channel aspect ratios, adapting to different structural depths without modifying the core optical architecture, and the modular platform offers strong scalability.

[0027] 2. High-fidelity reproduction of the chip's native optical parameters, with excellent economic efficiency for mass production. This invention features a mobile phone-grade lens group, which can reverse-engineer and precisely match core optical parameters such as the principal ray angle, imaging circle diameter (MIC), and relative illuminance (RI) based on the microlens characteristics of the CIS wafer pixels under test. The beam projected onto the wafer surface can reproduce the incident light field of the chip in real-world mobile terminal applications (such as mobile phone cameras) with high fidelity, ensuring accurate test data. The uniform light architecture of this invention eliminates the need for high-cost custom collimating lenses and is directly compatible with general standard mobile phone lenses or customer-supplied lenses, significantly reducing the overall material cost of the probe card array lighting module while meeting high-precision testing requirements.

[0028] 3. Achieve efficient quantitative calibration of multi-channel light intensity consistency, upgrading from traditional blind calibration based on experience to deterministic quantitative adjustment. Addressing the issue of inconsistent light intensity and illuminance caused by manufacturing tolerances in different channels during multi-chip parallel testing, this invention features an axial sliding locking ring with precise graduations. Technicians can use the graduations to perform micron-level quantitative fine-tuning of each independent station, quickly compensating for illuminance deviations caused by assembly stress and light source fluctuations. This eliminates the inefficient traditional method of replacing light-diffusing sheets one by one through trial and error, significantly improving the efficiency of multi-station lighting consistency calibration.

[0029] 4. Significantly improves the signal-to-noise ratio of the original image, relieves the pressure on the ISP algorithm from the source, suppresses noise, and can also improve the efficiency of CIS wafer inspection. The module has an independent and closed optical path, and each channel does not interfere with each other, making it suitable for various CIS wafer testing conditions. Attached Figure Description

[0030] Figure 1 This is a cross-sectional schematic diagram of an independent micro-illumination module for a CIS wafer test probe card in a specific embodiment of the present invention.

[0031] Figure 2 This is a schematic diagram of the reference optical path of an independent micro-illumination module for a CIS wafer test probe card in a specific embodiment of the present invention.

[0032] Figure 3 This is a three-dimensional structural diagram of the locking ring in a specific embodiment of the present invention.

[0033] In the figure: 01-CIS wafer under test; 10-Main light source, 20-Locking ring, 21-Groove, 30-Light guide post, 40-Light homogenizer, 50-Imaging lens, 60-Carrier housing, 61-Screw. Detailed Implementation

[0034] To illustrate the technical solutions of the invention in more detail, specific embodiments are listed below to demonstrate the technical effects; it should be emphasized that these embodiments are used to illustrate the invention and not to limit the scope of the invention.

[0035] The independent micro-illumination module for CIS wafer test probe cards provided by this invention, such as Figure 1 and Figure 2 As shown, the module includes a main light source 10, a locking ring 20, a light guide post 30, a light homogenizer 40, an imaging lens 50, and a carrier housing 60. The main light source 10, locking ring 20, light guide post 30, light homogenizer 40, and imaging lens 50 are arranged coaxially from top to bottom along the optical path. The CIS wafer 01 to be tested is correspondingly arranged below the module, and it can independently adapt to each test station of the probe card. Specifically:

[0036] The main light source 10 is located on the top of the module. In some embodiments, the main light source 10 may be a planar Lambertian light source to output a uniform and continuously adjustable beam. In this embodiment, the main light source has a steplessly adjustable illuminance of 0-10000 lux, which is suitable for the optical testing light source requirements of CIS chips.

[0037] Please refer to this carefully. Figure 3The locking ring 20 is a sleeve structure with a central through hole inside. It is fitted on the outer side of the upper end of the light guide post 30 and can slide along the optical path axis. The total amount of light entering the single channel can be adjusted by changing the distance between the main light source 10 and the upper end surface of the light guide post 30. The central through hole can also be used to limit the maximum solid angle of the incident light, block stray light with large angles from entering the optical path, and avoid distortion at the edge of the light spot.

[0038] The light guide post 30 is coaxially arranged below the locking ring 20. The inner wall of the light guide post 30 is a hexagonal polyhedral structure. Light is transmitted and mixed in three dimensions through multiple total internal reflections inside the light guide post 30, and finally outputs a high-uniformity flat-top light spot, thereby eliminating the mechanical vignetting and field-of-view interference problems caused by the obstruction of the inner hole wall of the traditional high aspect ratio probe card channel.

[0039] The light-diffusing sheet 40 is installed between the lower end of the light guide post 30 and the imaging lens 50. The light-diffusing sheet 40 is made of a high-haze volume scattering material to perform secondary angular scattering of the mixed light beam, thereby satisfying the field of view angle of the imaging lens.

[0040] The imaging lens 50 is coaxially positioned below the homogenizing plate 40 and is used to modulate the beam emitted after homogenization into a principal ray angle, imaging spot diameter, and relative illuminance that match the CIS wafer under test, and project it onto the photosensitive surface of the CIS wafer under test.

[0041] The carrier housing 60 covers and fixes the main light source 10, locking ring 20, light guide column 30, light homogenizer 40 and imaging lens 50. The carrier housing 60 as a whole can be fixed to the PCB carrier board by screws 61 to form a micro closed optical path channel that is independent and does not interfere with each other, isolates stray light crosstalk between workstations and reduces imaging noise.

[0042] In some embodiments, please refer to Figure 3 The locking ring 20 is provided with a locking component for fixing its axial position after the locking ring 20 has been slidably adjusted to the correct position. Specifically, two grooves 21 are symmetrically formed on the outer wall of the locking ring 20. The grooves 21 can match the positioning ribs on the inner side of the bearing housing 60 to achieve circumferential limiting and anti-rotation; on the other hand, when the locking component is a screw, the end of the screw can be pushed into the groove 21 to fix the axial position of the locking ring 20.

[0043] In some embodiments, the outer wall of the locking ring 20 is provided with a scale mark for quantifying the axial sliding distance; in multi-chip parallel testing scenarios, technicians rely on the scale to complete micron-level quantitative fine-tuning, abandoning the traditional blind adjustment method of replacing the light uniform sheet for trial and error, and greatly improving the efficiency of multi-station light intensity consistency calibration.

[0044] In some embodiments, the inner wall of the light guide post 30 is provided with a high-reflectivity film to further reduce beam transmission loss, improve light energy utilization, and ensure uniformity of output light spot brightness.

[0045] In some embodiments, the light guide post 30 includes various fixed axial length specifications, and different specifications of light guide posts 30 can be selected and replaced based on the probe card PCB thickness and the aspect ratio of the channel opening. Without modifying the core optical architecture composed of the main light source 10, locking ring 20, light homogenizer 40, and imaging lens 50, it can adapt to probe card channels of different depths, demonstrating strong modular expansion capabilities.

[0046] In some embodiments, the imaging lens 50 adopts a standard mass-produced lens or a customer-supplied lens, eliminating the need for a custom-made, expensive collimating lens. It can reverse-match the optical parameters such as the principal ray angle, imaging spot diameter, and relative illumination corresponding to the microlens of the 01 pixel of the CIS wafer under test, reproduce the actual light field used by the mobile terminal with high fidelity, and ensure the accuracy of the test data. At the same time, it reduces the overall material cost and has excellent economic efficiency in mass production.

[0047] In some embodiments, the housing 60 is provided with multiple positioning steps inside, and the main light source 10, locking ring 20, light guide column 30, light homogenizer 40 and imaging lens 50 are respectively limited by the positioning steps, which makes the assembly and alignment simple, the assembly error small, and the mass production assembly efficiency high.

[0048] In some embodiments, the lighting module further includes an ISP processor, which is used to acquire and process the imaging data output by the CIS wafer 01 under test, and calculate the illuminance deviation of each channel and the principal ray angle deviation based on the imaging data. Specifically, the operator controls the locking ring 20 to slide along the optical path axis based on the deviation value output by the ISP processor, thereby improving testing efficiency and accuracy.

[0049] In summary, the independent micro-lighting module for CIS wafer test probe cards provided by this invention achieves non-destructive three-dimensional uniform light through hexagonal polyhedral light guide pillars 30, adapting to various high aspect ratio probe card channels; and achieves multi-station quantitative light adjustment through a locking ring 20 with scale and double groove limiting and locking. The overall structure is modular, with high testing accuracy and low debugging and mass production costs, and is fully adaptable to the batch probe testing conditions of CIS wafers.

[0050] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A stand-alone miniature illumination module for a CIS wafer test probe card, characterized in that, Includes the main light source, locking ring, light guide column, light homogenizer, imaging lens, and supporting housing. The main light source is located on the top of the module; The locking ring is a sleeve structure, which is fitted onto the outer side of the upper end of the light guide post and can slide along the optical path axis. The total amount of light entering a single channel can be adjusted by changing the distance between the main light source and the upper end face of the light guide post. The light guide post is coaxially arranged below the locking ring. The inner wall of the light guide post has a hexagonal polyhedral structure. Light undergoes multiple total internal reflections inside the light guide post to complete three-dimensional beam mixing. The light-diffusing sheet is installed between the lower end of the light guide post and the imaging lens. The light-diffusing sheet is made of a high-haze volume scattering material to perform secondary angular scattering of the mixed light beam, thereby satisfying the field of view angle of the imaging lens. The imaging lens is coaxially positioned below the homogenizing plate and is used to modulate the beam emitted after homogenization into a principal ray angle, imaging spot diameter, and relative illuminance that match the CIS wafer under test, and project it onto the photosensitive surface of the CIS wafer under test. The supporting housing encloses and fixes the main light source, locking ring, light guide column, light homogenizer and imaging lens, forming a miniature closed optical path channel that is independent of each other and does not interfere with each other.

2. The independent micro-illumination module for CIS wafer test probe cards according to claim 1, characterized in that, The main light source is a planar Lambertian light source, used to output a uniform and continuously adjustable beam.

3. The independent micro-illumination module for CIS wafer test probe cards according to claim 1, characterized in that, The locking ring is provided with a locking component, which is used to fix its axial position after the locking ring is slidably adjusted into place.

4. The independent micro-illumination module for CIS wafer test probe cards according to claim 1, characterized in that, The outer wall of the locking ring is marked with scale markings to quantify the axial sliding distance.

5. The independent micro-illumination module for CIS wafer test probe cards according to claim 1, characterized in that, The inner wall of the light guide column is provided with a high-reflectivity film.

6. The independent micro-illumination module for CIS wafer test probe cards according to claim 1, characterized in that, The light guide column includes various fixed axial length specifications, and different specifications of light guide columns can be selected and replaced based on the probe card PCB thickness and the depth-to-width ratio of the channel opening.

7. The independent micro-illumination module for CIS wafer test probe cards according to claim 1, characterized in that, The imaging lens is a mobile phone lens.

8. The independent micro-illumination module for CIS wafer test probe cards according to claim 1, characterized in that, The housing is equipped with multiple positioning steps, and the main light source, locking ring, light guide, light homogenizer and imaging lens are respectively limited by the positioning steps.

9. The independent micro-illumination module for CIS wafer test probe cards according to claim 1, characterized in that, It also includes an ISP processor, which is used to acquire the imaging data output by the CIS wafer under test, and calculate the illuminance deviation and principal ray angle deviation of each channel based on the imaging data.

10. The independent micro-illumination module for CIS wafer test probe cards according to claim 9, characterized in that, The operator controls the locking ring to slide along the optical path axis based on the deviation value output by the ISP processor.

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